a small register · for things that resist the mouth
An unpronounceable is a sequence of letters that resists the mouth. It is not the same as a long word; some long words are perfectly easy. It is not the same as a foreign word; many foreign words are easy too. The unpronounceable is structurally hostile to vocalisation — it presents the reader with too many consonants, in the wrong order, with not enough vowels in between.
The unpronounceable belongs in the labyrinth because the labyrinth is generous about the relationship between the eye and the mouth. Many of the rooms here have names which can be read silently with no objection but, said aloud, would embarrass the reader. This is fine.
field note · the only unpronounceable that is regularly attempted aloud is the welsh one, and only by visitors who wish to be congratulated.